Summary:
Fix Image defaultSource not showing on iOS.
This bug was introduced somewhere between RN 0.63 and 0.65. On iOS, defaultSource does not show while the image is being downloaded, only if it fails or there's no internet.
## Changelog
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[iOS] [Fixed] - Fix Image defaultSource not showing on iOS
Pull Request resolved: https://github.com/facebook/react-native/pull/32172
Test Plan: Ran both debug and release builds on an iPhone 12 pro (iOS 14.6)
Reviewed By: sammy-SC
Differential Revision: D30822805
Pulled By: lunaleaps
fbshipit-source-id: c4ef18723a8311ef3be1d7ae25ff3c205e8fff62